Monday, 30 October at 1:00pm
Biochemistry Seminar Room BIG13
James Hodgkinson-Bean
Dept of Microbiology and Immunology
A tail of destruction: analysing novel structures of bacteriophage tail machinery (PhD Swansong)
Tailed bacteriophages of the class Caudoviricetes use intricate tail machinery to breach bacterial cell walls and facilitate infection. Depending on tail morphology, phages are categorised as either myophage, siphophage, or podophage. Myophages utilize a long contractile tail and intricate baseplate assembly to adhere to the cell surface and penetrate the bacterial cell wall through mechanical force. Alternatively, Podophages use enzymes to degrade outer cell structures and eject an internally packaged ‘ejectosome’ into the cell wall, forming a channel for safe genomic translocation. In both cases, the process of infection has primarily focused on well-studied model phages T4 and T7; however, Caudoviricetes represents the most abundant viral family on earth, and the degree of conservation of these mechanisms within morphotypes is largely unknown. During my PhD I investigated a range of bacteriophages with highly divergent structural modules relative to model phages. We used cryogenic electron microscopy to investigate these phages as complete virions, allowing in depth characterization of key sub-structures such as the myophage baseplate and podophage ejectosome. These studies revealed that these sub-structures can be highly divergent, containing additional gene products or structural motifs that likely alter infectious function. To summarise, our work sheds much light on the degree of structural divergence between myophages and podophages, informs on bacteriophage evolution, and identifies key differences in infectious machinery that may alter function
